Process for producing boron compounds

ABSTRACT

A method of producing a boron-based compound represented by general formula (1) including a first step of reacting lithium, magnesium or a compound containing lithium, a compound represented by general formula (2), and a compound represented by general formula (3): R 2  --Y to produce a borate metal salt represented by general formula (4), and a second step of adding to the borate metal salt an onium halide represented by general formula (5): Z +  ·X -   to effect ion exchange reaction (the symbols in the formulae have the same meanings as described in the specification). 
     According to the production method of the present invention, a high purity boron-based compound represented by the general formula (1) above useful as a photopolymerization initiator and a light-absorbing decolorizing agent can be obtained in a short time and a high yield as compared with the conventional method. ##STR1##

This application is the national phase of PCT/JP98/00477, filed Feb. 5,1998, now WO98/34938.

TECHNICAL FIELD

The present invention relates to a method of producing a boron-basedcompound and more particularly to a method of producing a boron-basedcompound useful as a photopolymerization initiator or a light-absorbingdecolorizing agent.

BACKGROUND ART

Photopolymerization is used in a variety of applications such ashardening of coated films, lithography, resin relief, and preparation ofprinted board, resist or photomask, black and white or color transferdevelopment or preparation of color developing sheet. Also, in the areaof dental technology, photopolymerizable compositions are used.

Photopolymerizable compositions comprise an ethylenically unsaturatedcompound and a photopolymerization initiator and usually they arepolymerized by means of ultraviolet rays.

For example, there has been known a polymerizable composition thatcontains an α-ketocarbonyl compound as a photopolymerization initiatorand hardens by irradiation of ultraviolet rays in the presence of aminessuch as N,N-dimethylaniline, which composition is used for producing adental filler and a dental sealant, for producing a crown or a bridge,and for producing dental prosthesis (Japanese Patent ApplicationLaid-open No. Sho 63-99858). Also, development of ultraviolet hardeningink has been made actively (Japanese Patent Application Laid-open No.Hei 2-22370).

However, such a photopolymerization as involving irradiation ofultraviolet rays has the problems that ultraviolet rays penetratemonomers insufficiently, ultraviolet rays generate ozone and causeirritation to the skin, and so on.

Accordingly, on photopolymerization initiators free of such problems,the applicant has previously filed a patent application relating to acomposition that comprising a boron compound (sensitizer) that caninitiate polymerization at high sensitivity with visible light and a(cationic) organic dye having an absorption in visible light region(Japanese Patent Application Laid-open No. Hei 5-59110) and a patentapplication relating to a composition comprising a boron compound thatcan initiate polymerization at high sensitivity with near-infrared lightand a near-infrared light-absorbing cationic dye (Japanese PatentApplication Laid-open No. Hei 5-194619).

Also, there has been developed a decolorizing agent that utilizes thephenomenon that the reaction between a dye and a boron-based compoundwith near-infrared light causes the color of the dye to disappear(Japanese Patent Application Laid-open No. Hei 4-362935) and it isapplied to toners and inks that allow reuse of a recording material.

The above-mentioned photopolymerization initiator or decolorizing agentuses as the boron-based compound (sensitizer) a compound represented bygeneral formula (A) ##STR2## (wherein R^(1A), R^(2A), R^(3A), and R^(4A)independently represent an alkyl group, an aryl group, an alkaryl group,an allyl group, an aralkyl group, an alkenyl group, an alicyclic groupor a saturated or unsaturated heterocyclic group or the like, R^(5A),R^(6A), R^(7A), and R^(8A) independently represent a hydrogen atom, analkyl group, an aryl group, an alkaryl group, an allyl group, an aralkylgroup an alkenyl group, an alicyclic group, or a saturated orunsaturated heterocyclic group or the like); of these compounds, thosein which at least one of R^(1A), R^(2A), R^(3A), and R^(4A) representsan alkyl group and the remaining groups are each an aryl group arepreferred.

As a general method of producing tetramethylammonium methyl triphenylborate (R^(1A) =a methyl group, R^(2A) =R^(3A) =R^(4A) =a phenyl group,R^(5A) =R^(6A) =R^(7A) =R^(8A) =a methyl group), one of such preferredcompounds, there has been known a method in which lithium methyltriphenyl borate obtained from triphenylborane and methyllithium ision-exchanged with tetramethylammonium bromide [for example, Journal ofthe American Chemical Society, Vol. 107, page 6710 (1985)].

Also, as the method of producing triphenylborane, i.e., startingmaterial, there has been generally known a method in which magnesium,boron trifluoride diethyl etherate, and phenyl bromide are reacted indiethyl ether [for example, Journal of Organic Chemistry, Vol. 51, page427 (1986)].

In the case of the tetramethylammonium methyl triphenyl borate,concretely, its production is performed by reacting phenyl bromide withmagnesium in diethyl ether to prepare a Grignard reagent, dripping it ina solution of boron trifluoride diethyl etherate in diethyl ether, andthen stirring for several hours to obtain triphenylborane, followed byaddition of methyllithium without isolating triphenylborane to convertit to lithium methyl triphenyl borate and by addition oftetramethylammonium bromide to effect ion exchange to obtaintetramethylammonium methyl triphenyl borate.

In such conventional production methods, diethyl ether is exclusivelyused as a solvent for a Grignard reaction or a triarylborane ortrialkylborane reaction. This is because when use is made oftetrahydrofuran, in which the reaction is generally supposed to tend tooccur more readily than in diethyl ether, the reaction does not stopwhen triaryl (or trialkyl) borane is produced but proceeds untiltetraaryl (or tetraalkyl) borate is produced [for example, Journal ofOrganic Chemistry, Vol. 51, page 427 (1986)].

However, there arises the problem that a Grignard reaction is difficultto occur in diethyl ether depending on the type of halide to be used sothat it takes a long time for the production and the final yield of thetarget boron-based compound is decreased.

OBJECT OF THE INVENTION

An object of the present invention is to obviate these problemsassociated with the conventional production methods and to provide aproduction method that enables one to obtain a highly pure boron-basedcompound useful as a photopolymerization initiator or light-absorbingdecolorizing agent in a high yield for a short time.

DISCLOSURE OF THE INVENTION

As a result of intensive research with view to dissolving theabove-mentioned problems, the present inventors have found that theabove-described object can be achieved by performing reaction using aspecified starting material, reaction solvent and reaction step, therebycompleting the present invention.

That is, the present invention provides:

1) A method of producing a boron-based compound represented by generalformula (1) ##STR3## (wherein R¹ and R² independently represent an alkylgroup which may have a substituent group, an alkenyl group which mayhave a substituent group, an aryl group which may have a substituentgroup, an aralkyl group which may have a substituent group, aheterocyclic group which may have a substituent group, or an alicyclicgroup which may have a substituent group provided that R¹ and R² aredifferent from each other and Z⁺ represents an ammonium cation, apyridinium cation, a sulfonium cation, an oxosulfonium cation, aphosphonium cation, or a iodonium cation), comprising a first step ofreacting lithium, magnesium or a compound containing lithium, a compoundrepresented by general formula (2) ##STR4## (wherein R¹ has the samemeaning as defined above, R⁷ and R⁸, which may be the same or different,each represent an alkyl group which may have a substituent group, analkenyl group which may have a substituent group, an aryl group whichmay have a substituent group, an aralkyl group which may have asubstituent group, or an alicyclic group which may have a substituentgroup, or R⁷ and R⁸ combine with each other together with the boron atomand oxygen atoms to which they are attached to form a cyclic structure),and a compound represented by general formula (3)

    R.sup.2 --Y                                                (3)

(wherein R² has the same meaning as defined above but is different fromR¹ in the general formula (2) above and Y represents a hydrogen atom ora halogen atom) to produce a borate metal salt represented by generalformula (4) ##STR5## (wherein R¹ and R² have the same meanings asdefined above, M is lithium or magnesium and n is 1 when M is lithium or2 when M is magnesium), and a second step of adding to the borate metalsalt an onium halide represented by general formula (5)

    Z.sup.+ ·X.sup.-                                  (5)

(wherein Z⁺ has the same meaning as defined above and X⁻ represents ahalide anion) to effect ion exchange reaction.

2) The method of producing a boron-based compound represented by generalformula (1) as described in 1) above, wherein the onium haliderepresented by the general formula (5) is an ammonium halide representedby general formula (6) ##STR6## (wherein X⁻ has the same meaning asdefined above and R³, R⁴, R⁵, and R⁶ independently represent an alkylgroup which may have a substituent group, an aryl group which may have asubstituent group, an aralkyl group which may have a substituent group,or an alicyclic group which may have a substituent group).

3) The method of producing a boron-based compound represented by thegeneral formula (1) as described in 1) or 2) above, wherein in the firststep, lithium, magnesium or the compound containing lithium and thecompound represented by the general formula (3) are reacted in a solventand then the compound represented by the general formula (2) is added toobtain the borate metal salt represented by the general formula (4).

4) The method of producing a boron-based compound represented by thegeneral formula (1) as described in 1) or 2) above, wherein in the firststep, a product obtained by reacting lithium, magnesium or the compoundcontaining lithium and the compound represented by the general formula(3) in a solvent is added to the compound represented by the generalformula (2) to obtain the borate metal salt represented by the generalformula (4).

5) The method of producing a boron-based compound represented by thegeneral formula (1) as described in 1) or 2) above, wherein in the firststep, lithium, magnesium or the compound containing lithium and thecompound represented by the general formula (3) are reacted in a solventin the presence of the compound represented by the general formula (2)to obtain the borate metal salt represented by the general formula (4).

6) The method of producing a boron-based compound represented by thegeneral formula (1) as described in any of 1) to 5) above, wherein inthe first step, lithium or magnesium is used and a halide is used as thecompound represented by the general formula (3).

7) The method of producing a boron-based compound represented by thegeneral formula (1) as described in any of 1) to 5) above, wherein inthe first step, an organic lithium compound is used and a halide is usedas the compound represented by the general formula (3).

DETAILED DESCRIPTION OF THE INVENTION

R¹ and R² in the general formula (1) above that represents theboron-based compound produced by the method of the present inventionindependently represent an alkyl group which may have a substituentgroup, an alkenyl group which may have a substituent group, an arylgroup which may have a substituent group, an aralkyl group which mayhave a substituent group, a heterocyclic group which may have asubstituent group, or an alicyclic group which may have a substituentgroup. Note that R¹ and R² differ from each other.

Z⁺ represents an ammonium cation, a pyridinium cation, a sulfoniumcation, an oxosulfonium cation, a phosphonium cation, or a iodoniumcation. Preferred Z⁺ is an ammonium cation represented by generalformula (7). ##STR7##

In the general formula (7), R³, R⁴, R⁵, and R⁶ independently representan alkyl group which may have a substituent group, al aryl group whichmay have a substituent group, an aralkyl group which may have asubstituent group, or an alicyclic group which may have a substituentgroup.

The alkyl group which may have a substituent group represented by R¹ andR² is preferably a substituted or unsubstituted, straight or branchedchain alkyl group having 1 to 10 carbon atoms and specific examplesthereof include methyl, ethyl, propyl, isopropyl, butyl, isobutyl,sec-butyl, pentyl, hexyl, heptyl, octyl, 3-methoxypropyl, 4-chlorobutyl,2-diethylaminoethyl, etc. groups.

The alkenyl group which may have a substituent group represented by R¹and R² is preferably substituted or unsubstituted and has 2 to 12 carbonatoms. Specific examples thereof include vinyl, propenyl, butenyl,pentenyl, hexenyl, heptenyl, octenyl, dodecenyl, prenyl, etc. groups.

The aryl group which may have a substituent group represented by R¹ andR² is a substituted or unsubstituted aryl group and specific examplesthereof include phenyl, tolyl, xylyl, 4-ethylphenyl, 4-butylphenyl,4-tert-butylphenyl, 4-methoxyphenyl, 4-diethylaminophenyl,2-methylphenyl, 2-methoxyphenyl, naphthyl, 4-methylnaphthyl, etc.groups.

The aralkyl group which may have a substituent group represented by R¹and R² is a substituted or unsubstituted aralkyl group and specificexamples thereof include benzyl, phenethyl, propiophenyl,α-naphthylmethyl, β-naphthylmethyl, p-methoxybenzyl, etc. groups.

The heterocyclic group which may have a substituent group represented byR¹ and R² is a substituted or unsubstituted heterocyclic group andspecific examples thereof include pyridyl, quinolyl, methylpyridyl,indolyl, etc. groups.

The alicyclic group which may have a substituent group represented by R¹and R² is a substituted or unsubstituted alicyclic group and specificexamples thereof include cyclohexyl, 4-methylcyclohexyl, cyclopentyl,cycloheptyl, etc. groups.

Specific examples of the ammonium cation of which Z⁺ in the generalformula (1) above is represented by the general formula (7) includetetramethylammonium cation, tetraethylammonium cation,tetrapropylammonium cation, tetra-n-butylammonium cation,tetra-n-pentylammonium cation, tetra-n-octylammonium cation,tetrabenzylammonium cation, tetraphenylammonium cation,tetracyclohexylammonium cation, triphenylphenacylammonium cation,triphenyl(4-aminophenyl)ammonium cation, etc.

Specific examples of the sulfonium cation represented by Z⁺ in thegeneral formula (1) above include dimethyl-tert-butylsulfonium cation,dimethylbenzylsulfonium cation, dimethyl(4-chlorobenzyl)sulfoniumcation, dibutyl(4-bromobenzyl)sulfonium cation,dimethyl(4-cyanobenzyl)sulfonium cation, dimethylphenacylsulfoniumcation, tributylsulfonium cation, triphenylsulfonium cation, etc.

Specific examples of the pyridinium cation represented by Z⁺ in thegeneral formula (1) above include N-methylpyridinium cation,N-ethylpyridinium cation, N-n-propylpyridinium cation,N-n-butylpyridinium cation, etc.

Specific examples of the oxosulfonium cation represented by Z⁺ in thegeneral formula (1) above include dimethyl-tert-butyloxosulfoniumcation, dimethylbenzyloxosulfonium cation,dimethyl(4-chlorobenzyl)oxosulfonium cation,dibutyl(4-bromobenzyl)oxosulfonium cation,dimethyl(4-cyanobenzyl)oxosulfonium cation, dimethylphenacyloxosulfoniumcation, tributyloxosulfonium cation, triphenyloxosulfonium cation, etc.

Specific examples of the phosphonium cation represented by Z⁺ in thegeneral formula (1) above include tetramethylphosphonium cation,tetraethylphosphonium cation, tetrapropylphosphonium cation,tetra-n-butylphosphonium cation, tetra-n-pentylphosphonium cation,tetra-n-octylphosphonium cation, tetrabenzylphosphonium cation,tetraphenylphosphonium cation, tetracyclohexylphosphonium cation,triphenylphenacylphosphonium cation, triphenyl(4-aminophenyl)phosphoniumcation, etc.

Specific examples of the iodonium cation represented by Z⁺ in thegeneral formula (1) above include diphenyliodonium cation,4-butoxyphenyl(4'-methylphenyl)iodonium cation,bis(4-aminophenyl)iodonium cation, etc.

Specific examples of the boron-based compounds represented by thegeneral formula (1) include

tetramethylammonium ethyl tri-n-butyl borate,

tetra-n-butylammonium phenethyl trimethyl borate,

tetraethylammonium phenyl truisobutyl borate,

tetra-n-butylammonium phenethyl tri(4-methylphenyl)borate,

tetramethylammonium ethyl triphenyl borate,

tetraethylammonium n-octyl tri(4,5-diethylphenyl)borate,

tetra-n-butylammonium n-pentyl tri(4-methoxyphenyl)borate,

tetra-n-octylammonium n-butyl tri-1-naphthyl borate,

tetra-n-butylammonium n-butyl tri(4-methyl-1-naphthyl)borate,

tetraethylammonium n-octyl tri(4,5-diethyl-1-naphthyl)borate,

tetra-n-butylammonium ethyl triacenaphthyl borate,

N-methylpyridinium n-butyl triphenyl borate,

triphenylsulfonium n-butyl tri(1-naphthyl)borate,

triphenyloxosulfonium n-butyl tri(1-naphthyl)borate,

tetra-n-butylsulfonium n-butyl triphenyl borate,

diphenyliodonium n-butyl triphenyl borate, etc.

R¹ in the general formula (2) above is the same as R¹ in the generalformula (1) above. R⁷ and R⁸ in the general formula (2) above, which maybe the same or different, R⁷ and R⁸, which may be the same or different,each represent an alkyl group which may have a substituent group, analkenyl group which may have a substituent group, an aryl group whichmay have a substituent group, an aralkyl group which may have asubstituent group, or an alicyclic group which may have a substituentgroup, or R⁷ and R⁸ combine with each other together with the boron atomand oxygen atoms to which they are attached to form a cyclic structure.

The alkyl group which may have a substituent group represented by R⁷ andR⁸ is preferably a substituted or unsubstituted, straight or branchedchain alkyl group having 1 to 10 carbon atoms and specific examplesthereof include methyl, ethyl, propyl, isopropyl, butyl, isobutyl,sec-butyl, pentyl, hexyl, heptyl, octyl, 3-methoxypropyl, 4-chlorobutyl,2-diethylaminoethyl, etc. groups.

The alkenyl group which may have a substituent group represented by R⁷and R⁸ is a substituted or unsubstituted alkenyl group and haspreferably 2 to 12 carbon atoms. Specific examples thereof includevinyl, propenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl,dodecenyl, prenyl, etc. groups.

The aryl group which may have a substituent group represented by R⁷ andR⁸ is a substituted or unsubstituted aryl group and specific examplesthereof include phenyl, tolyl, xylyl, 4-ethylphenyl, 4-butylphenyl,4-tert-butylphenyl, 4-methoxyphenyl, 4-diethylaminophenyl,2-methylphenyl, 2-methoxyphenyl, naphthyl, 4-methylnaphthyl, etc.groups.

The aralkyl group which may have a substituent group represented by R⁷and R⁸ is a substituted or unsubstituted aralkyl group and specificexamples thereof include benzyl, phenethyl, propiophenyl,α-naphthylmethyl, β-naphthylmethyl, p-methoxybenzyl, etc. groups.

The alicyclic group which may have a substituent group represented by R⁷and R⁸ is a substituted or unsubstituted alicyclic group and specificexamples thereof include cyclohexyl, 4-methylcyclohexyl, cyclopentyl,cycloheptyl, etc. groups.

Specific examples of the compound represented by the general formula (2)above include dimethyl ethyl boronate, diethyl n-propyl boronate,diisopropyl n-butyl boronate, diisobutyl methyl boronate, di-n-octylbenzyl boronate, di(2-phenethyl)n-butyl boronate, diphenyl n-propylboronate, diisopropyl phenyl boronate, diethyl(4-methoxyphenyl)boronate,dicyclohexyl n-octyl boronate, etc.

Specific examples of the compound having a cyclic structure representedby R⁷ and R⁸ together with the boron atom and oxygen atoms to which theyare attached include 2-methyl-1,3,2-dioxaborinane,2-ethyl-1,3,2-dioxaborinane, 2-n-propyl-1,3,2-dioxaborinane,2-n-butyl-1,3,2-dioxaborinane, 2-phenyl-1,3,2-dioxaborinane,2-naphthyl-1,3,2-dioxaborinane, etc.

R² in the general formula (3) above is the same as R² in the generalformula (1) above and Y represents a hydrogen atom or a halogen atom.

The compound represented by the general formula (3) above includeshalides of saturated or unsaturated aliphatic hydrocarbons, halides ofalicyclic hydrocarbons, halides of aromatic hydrocarbons, aromatichydrocarbons, heterocyclic aromatic compounds, etc. Specific examplesthereof include methyl bromide, ethyl chloride, propyl chloride,isopropyl chloride, butyl chloride, isobutyl bromide, pentyl bromide,hexyl bromide, octyl chloride, 2-bromoethyl methyl ether, vinyl bromide,propenyl bromide, butenyl bromide, pentenyl bromide, hexenyl bromide,heptenyl bromide, octenyl bromide, bromobenzene, iodobenzene,bromotoluene, bromoxylene, 1-bromo-4-ethylbenzene,1-bromo-4-butylbenzene, 1-bromo-4-tert-butylbenzene,1-bromo-4-methoxybenzene, 1-bromo-4-diethylaminobenzene,1-bromo-2-methylbenzene, 1-bromo-2-methoxybenzene, 1-bromonaphthalene,2-bromonaphthalene, 1-bromo-4-methylnaphthalene, benzyl chloride,phenethyl bromide, 1-bromo-3-phenylpropane, 1-(bromomethyl)naphthalene,2-(bromomethyl)naphthalene, p-methoxybenzyl chloride, cyclohexylchloride, 1-chloro-4-methylcyclohexane, benzene, toluene, xylene,ethylbenzene, butylbenzene, tert-butylbenzene, methoxybenzene,diethylaminobenzene, ethoxybenzene, naphthalene, 1-methylnaphthalene,cyclopentadiene, indene, fluorene, furan, thiophene, etc.

Specific examples of the onium halide represented by the general formula(5) include tetramethylammonium bromide, tetraethylammonium bromide,tetra-n-propylammonium iodide, tetra-n-butylammonium bromide,tetra-n-pentylammonium chloride, tetra-n-octylammonium bromide,tetrabenzylammonium bromide, tetraphenylammonium bromide,tetracyclohexylammonium bromide, N-methylpyridinium chloride,N-butylpyridinium bromide, dimethyl-tert-butylsulfonium bromide,dimethylbenzylsulfonium bromide, dimethyl(4-chlorobenzyl)sulfoniumbromide, dibutyl(4-bromobenzyl)sulfonium chloride,dimethyl(4-cyanobenzyl)sulfonium bromide, dimethylphenacylsulfoniumchloride, tributylsulfonium chloride, triphenylsulfonium chloride,tributylsulfonium bromide, triphenylsulfonium bromide,dimethyl-tert-butyloxosulfonium bromide, dimethylbenzyloxosulfoniumbromide, dimethyl(4-chlorobenzyl)oxosulfonium chloride,dibutyl(4-dimethyl(4-cyanobenzyl)oxosulfonium chloride,dimethylphenacyloxosulfonium chloride, tributyloxosulfonium chloride,triphenyloxosulfonium chloride, tributyloxosulfonium bromide,triphenyloxosulfonium bromide, tetramethylphosphonium chloride,tetraethylphosphonium chloride, tetra-n-propylphosphonium chloride,tetra-n-butylphosphonium bromide, tetra-n-pentylphosphonium bromide,tetra-n-octylphosphonium chloride, tetrabenzylphosphonium chloride,tetraphenylphosphonium iodide, tetracyclohexylphosphonium bromide,tetraphenylphosphonium bromide, triphenylphenacylphosphonium chloride,triphenyl(4-aminophenyl)phosphonium bromide, diphenyliodonium chloride,4-butoxyphenyl(4'-methylphenyl)iodonium chloride,bis(4-aminophenyl)iodonium chloride, etc.

R¹ and R² in the general formula (4) representing the borate metal salthave the same meanings as defined above. M represents a lithium ormagnesium atom and n is 1 when M is lithium or 2 when M is magnesium.

In the present invention, the compound containing lithium used in thefirst step is an organic lithium compound such as an alkyllithium or anaryllithium. Specific examples thereof include methyllithium,n-butyllithium, phenyllithium, etc. Of these, preferred isn-butyllithium.

The solvent used in the present invention includes, for example,ether-based solvents such as diethyl ether, n-butyl ethyl ether,di-n-propyl ether, diisopropyl ether, di-n-butyl ether,1,2-dimethoxyethane, tetrahydrofuran, and 1,4-dioxane, hydrocarbon-basedsolvents such as n-hexane, aromatic-based solvents such as benzene,toluene, and xylene. Of these, diethyl ether, tetrahydrofuran, hexane,and toluene are used preferably.

According to the method of the present invention, first, in the firststep, lithium, magnesium or the compound containing lithium and thecompound represented by the general formula (2), and the compoundrepresented by the general formula (3) are reacted to produce the boratemetal salt represented by the general formula (4), an intermediate.

More specifically, the first step is carried out, for example, by thefollowing methods:

(a) A method in which lithium, magnesium or the compound containinglithium and the compound represented by the general formula (3) arereacted in a solvent and thereafter the compound represented by thegeneral formula (2) is added thereto for reaction to obtain the compoundrepresented by the general formula (4),

(b) A method in which to the compound represented by the general formula(2) is added a product obtained by reacting lithium, magnesium or thecompound containing lithium and the compound represented by the generalformula (3) in a solvent to obtain the compound represented by thegeneral formula (4), and

(c) A method in which lithium, magnesium or the compound containinglithium and the compound represented by the general formula (3) arereacted in a solvent in the presence of the compound represented by thegeneral formula (2) to obtain the borate metal salt represented by thegeneral formula (4).

Next, in the second step, to the previously obtained borate metal saltintermediate represented by the general formula (4) is added the oniumhalide represented by the general formula (5) to effect ion exchangereaction to produce the boron-based compound represented by the generalformula (1).

More specifically, for example, use of magnesium and a halide as thecompound represented by the general formula (3) and reaction by any ofthe methods (a), (b) or (c) above in the first step enables productionof a borate magnesium salt intermediate represented by the generalformula (4) in which M is Mg and n is 2.

Also, use of lithium and a halide as the compound represented by thegeneral formula (3) and reaction by the method (a) or (b) in the firststep enables production of a borate lithium salt intermediaterepresented by the general formula (4) in which M is Li and n is 1.

Also, use of an organic lithium compound and a halide as the compoundrepresented by the general formula (3) and reaction by the method (a) or(b) in the first step also enables a borate lithium salt intermediaterepresented by the general formula (4) in which M is Li and n is 1.

Use of a halide as the compound represented by the general formula (3)generally increases yield.

An example of reaction for producing a borate magnesium saltintermediate represented by the general formula (4) in which M is Mg andn is 2 using magnesium will be described concretely.

In this case, the reaction between (a), (b) and (c) is a reaction forpreparing a Grignard reagent. Accordingly, the compound represented bythe general formula (3) must be a halide.

Addition of a small amount of an ether solution of a halide to magnesiumand stirring results in an elevation in reaction temperature before longand reaction (Grignard reaction) starts. If the reaction is difficult tooccur, iodine, methyl iodide, etc. may be added as an initiator. Thereaction temperature is preferably near the boiling point of the solventto be used and an ether-based solution of the halide is added so thatthis temperature can be maintained.

For example, in tetrahydrofuran, it is desirable to add atetrahydrofuran solution of halide so that the reaction proceeds at atemperature near 67 to 72° C. After the addition of the ether solutionof halide the resulting mixture is stirred at a temperature from roomtemperature to near the boiling point of the solvent for about 30minutes to about 20 hours to complete the reaction. The compound thusprepared is a Grignard reagent.

In the case of the reaction (a) above, a solution of the compoundrepresented by the general formula (2) (preferably a solution using thesame solvent as the solvent used for the Grignard reaction) is added tothe Grignard reagent such that the reaction temperature will be fromroom temperature to near the boiling point of the solvent used and afterthe addition, the mixture is allowed to react at from room temperatureto near the boiling point of the solvent for about 30 minutes to about 2hours, thereby completing the first step.

In the case of the reaction (b) above, to a solution of the compoundrepresented by the general formula (2) (preferably the same solvent asthe solvent used for the Grignard reaction) is added the Grignardreagent such that the reaction temperature will be at from roomtemperature to near the boiling point of the solvent used and after theaddition, the mixture is allowed to react at from room temperature tonear the boiling point of the solvent for about 30 minutes to about 2hours, thereby completing the first step.

In the case of the reaction (c) above, addition of a small amount of anether solution of a halide to magnesium and the compound represented bythe general formula (2) and stirring results in an elevation in reactiontemperature before long and reaction (Grignard reaction) starts. If thereaction is difficult to occur, iodine, methyl iodide, etc. may be addedas an initiator. The reaction temperature is preferably near the boilingpoint of the solvent to be used and an ether-based solution of thehalide is added so that this temperature can be maintained. For example,in tetrahydrofuran, it is desirable to add a tetrahydrofuran solution ofa halide so that the reaction proceeds at a temperature near 67 to 72°C. After the addition of the ether solution of a halide the resultingmixture is stirred at a temperature from room temperature to near theboiling point of the solvent for about 30 minutes to about 20 hours tocomplete the first step.

As described above, when a Grignard reaction using magnesium is to bepassed through, the compound represented by the general formula (3) mustbe a halide.

In the conventional method, the solvent for Grignard reactions islimited to diethyl ether as described above. On the contrary, in thepresent invention, it is possible to use as a solvent tetrahydrofuran orthe like, in which Grignard reactions tend to occur more readily, sothat the reaction time is shortened and yield increases.

When lithium or an organic lithium compound is used instead ofmagnesium, the compound represented by the general formula (3) does nothave to be a halide. However, when the compound represented by thegeneral formula (3) is a halide, substitution of a halogen by lithiumproceeds selectively as described later on.

When the compound represented by the general formula (3) is not ahalide, it is considered that there are a plurality of organic lithiumcompounds that have been lithiated with lithium or an organic lithiumcompound (for example, in the case of lithiation oftrifluoromethylbenzene, there are at least three kinds of lithiumcompounds) and hence yield is increased when the compound represented bythe general formula (3) is a halide.

An example of reaction for producing an intermediate compoundrepresented by the general formula (4) in which M is Li and n is 1 usinglithium will be described concretely.

This intermediate compound can be produced by use of lithium and ahalide as the compound represented by the general formula (3) and bymeans of the method (a) or (b) above in the first step. In this case, asthe solvent there can be used ether-based solvents such as diethyl etherand solvents such as tetrahydrofuran and solvents such as hexane andcyclohexane. In this case, generally the reaction is carried out in thepresence of an inert gas at from about -100° C. to about roomtemperature.

More specifically, such a solvent as described above is added to lithiumand a halide solution is added thereto. The reaction temperature mayvary depending on the halide and solvent used. For example, in thereaction between lithium and dibromobenzene in diethyl ether, it isdesirable to add a diethyl ether solution of bromobenzene such that thereaction temperature will be from -78 to -70° C. After addition of thehalide solution, the resulting mixture is stirred at from about -100° C.to about room temperature for about 30 minutes to about 2 hours toprepare an organic lithium compound.

And in the case of the reaction (a) above, a solution of the compoundrepresented by the general formula (2) in such a solvent as describedabove (preferably, an ether-based solution) is added to the organiclithium compound such that the reaction temperature will be preferablyabout -100° C. to about room temperature and after the addition, themixture is allowed to react at from about -100° C. to about roomtemperature for about 30 minutes to about 2 hours to complete the firststep.

In the case of the reaction (b) above, an organic lithium compound isadded to a solution of the compound represented by the general formula(2) in such a solvent as described above (preferably, an ether-basedsolvent) such that the reaction temperature will be preferably fromabout -100° C. to about room temperature and after the addition, themixture is allowed to react at from about -100° C. to about roomtemperature for about 30 minutes to about 2 hours to complete the firststep.

Next, an example of reaction for producing an intermediate representedby the general formula (4) in which M is Li and n is 1 using an organiclithium compound will be described concretely.

This intermediate compound can also be produced by use of an organiclithium compound and an aromatic halide as the compound represented bythe general formula (3) as described above and by means of the method(a) or (b) above in the first step.

Some of the organic lithium compounds are put on the market in the formof a hexane solution, a cyclohexane solution, a diethyl ether solution,etc. and readily available.

When organic lithium compounds are used, the reaction solvent which canbe used includes ether-based solvents such as diethyl ether andtetrahydrofuran, solvents such as cyclohexane, etc.

Generally, the reaction proceeds in an inert gas atmosphere at fromabout -100° C. to about room temperature. A solution of halide is addedto a solution of organic lithium compound such that the reactiontemperature will be from about -100° C. to about room temperature toprepare an organic lithium compound. The reaction temperature may varydepending on the halide and solvent to be used. For example, thereaction of n-butyllithium and 1-bromo-2,5-dimethylbenzene in diethylether is desirably performed by addition of a diethyl ether solution of1-bromo-2,5-dimethylbenzene such that the reaction occurs at from -78 to-10° C. After the addition is completed, the resulting mixture isfurther stirred at from about -100° C. to about room temperature forabout 30 minutes to about 2 hours to prepare an organic lithiumcompound. Also, an organic compound can be prepared by adding a solutionof organic lithium compound to a solution of halide under similarconditions.

In the case of the reaction (a), a solution of the compound representedby the general formula (2) in such a solvent as described above(preferably, an ether-based solution) is added to the organic lithiumcompound such that the reaction temperature will be preferably fromabout -100° C. to about room temperature and after the addition, themixture is allowed to react at from about -100° C. to about roomtemperature for about 30 minutes to about 2 hours to complete the firststep.

In the case of the reaction (b) above, an organic lithium compound isadded to a solution of the compound represented by the general formula(2) in such a solvent as described above (preferably, an ether-basedsolvent) such that the reaction temperature will be preferably fromabout -100° C. to about room temperature and after the addition, themixture is allowed to react at from about -100° C. to about roomtemperature for about 30 minutes to about 2 hours to complete the firststep.

More specifically, the second step in the present invention can proceed,for example, as follows.

The intermediate compound (borate metal salt) represented by the generalformula (4) after the completion of the first step is distributed inwater and a suitable organic solvent (preferably, ethyl acetate ordiethyl ether) and 1.2 to 5 equivalents of the onium halide representedby the general formula (5) is added to the aqueous phase, followed byvigorous stirring to cause ion exchange of the metal cation portion ofborate with the onium cation. Further, the reaction mixture is washedwith water once or twice and only the organic layer is distilled offunder reduced pressure. To the residue is added a solvent such asdiethyl ether, hexane or methanol and the precipitates are filtered andwashed with a solvent such as diethyl ether or hexane.

According to the conventional production method, for example, in thecase the compound represented by the general formula (1) istetra-n-butylammonium n-butyl tri(4-methylphenyl)borate, it is sometimesthe case that tetra(4-methylphenyl)borate is by-produced as a result ofa side reaction upon production of tri(4-methylphenyl)borane so thatyield is decreased. On the contrary, according to the method of thepresent invention, there is no possibility that the side reaction willoccur so that a high purity boron-based compound can be obtained.

Use of the production method of the present invention not only increasesyield but also shortens production time as compared with theconventional method.

For example, in the case of the above-mentioned tetra-n-butylammoniumn-butyl tri(4-methylphenyl)borate, the conventional method is carriedout by (i) adding to magnesium a diethyl ether solution of4-bromotoluene to prepare a Grignard reagent, (ii) reacting the Grignardreagent with boron trifluoride diethyl etherate in diethyl ether toderive it to a triarylborane, (iii) further reacting the triarylboranewith an organic metal compound selected from n-butylmagnesium chloride,n-butylmagnesium bromide, n-butylmagnesium iodide and n-butyllithium toderive it to n-butyl tri(4-methylphenyl)borate metal salt, and then (iv)subjecting the borate metal salt to ion exchange withtetra-n-butylammonium bromide to obtain the target compound(tetra-n-butylammonium n-butyl tri(4-methylphenyl)borate). Therefore,the conventional method comprises 4 steps and it takes about 10 hoursfor the production in this case.

On the other hand, in the case of the production method of the presentinvention, in particular, in the case where a halide is used as thecompound represented by the general formula (3) and magnesium and thehalide represented by the general formula (3) are reacted in thepresence of the compound represented by the general formula (2) intetrahydrofuran, a tetrahydrofuran solution of 4-bromotoluene is addedto magnesium and diisopropyl n-butyl boronate to cause Grignard reactionand derive the boronate to n-butyl tri(4-methylphenyl)borate metal salt(the first step). Then, theboratemetal salt is subjected to ion exchangewith tetra-n-butylammonium bromide, which enables one to obtaintetra-n-butylammonium n-butyl tri(4-methylphenyl)borate, the targetcompound (the second step). Therefore, the target compound can beproduced in 2 steps so that production in a short time of about 4 hours,for example, is possible.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereafter, the present invention will be described in more detail byexample. However, the present invention should not be limited to thefollowing examples without departing from the gist of the presentinvention.

EXAMPLE 1

Production of tetra-n-butylammonium methyl tri(4-methylphenyl)borate

First Step

To 1.00 g (41.1 mmol) of magnesium were added 10 mg of iodine and 10 mlof tetrahydrofuran. To this was added dropwise a solution of 5.64 g(33.0 mmol) of 4-bromotoluene in 20 ml of tetrahydrofuran in a nitrogenatmosphere such that the reaction temperature was from 67 to 72° C. andthe mixture was further stirred at from 30 to 50° C. for 2 hours. Tothis was added 1.00 g (10.0 mmol) of 2-methyl-1,3,2-dioxaborinane at thesame temperature as above and the resulting mixture was further stirredat from 30 to 50° C. for 2 hours.

Second Step

When the reaction mixture was cooled to room temperature, 200 ml ofdiethyl ether was added and then 50 ml of water was added portionwise.The reaction mixture was transferred into a separatory funnel and washedwith 80 ml of water, 60 ml of an aqueous 0.2 M tetra-n-butylammoniumbromide solution, and 80 ml of water in order, and then concentrated. Tothe residue was added 200 ml of diethyl ether and the solids whichprecipitated were filtered to obtain 5.00 g (9.23 mmol) of the targetcompound as white solids in a yield of 92%.

Measurement of mass spectrum of the product gave a value of 299 for theanion portion and 242 for the cation portion, thus showing coincidencewith the calculated values. Also, elemental analysis indicatedcoincidence with the calculated values.

Elemental Analysis:

    ______________________________________                                        Calculated (%)                                                                             C 84.26 H 11.26   N 2.59                                                                              B 2.00                                     Found (%) C 84.11 H 11.31 N 2.44 B 2.14                                     ______________________________________                                    

EXAMPLE 2

Production of tetramethylammonium n-butyl tri-n-octyl borate

First Step

To 1.00 g (41.1 mmol) of magnesium was added dropwise a solution of 4.91g (33.0 mmol) 1-chlorooctane in 20 ml of diethyl ether in a nitrogenatmosphere to prepare a Grignard reagent.

The Grignard reagent was added dropwise in a solution of 1.86 g (10.0mmol) of diisopropyl n-butyl boronate in 10 ml of tetrahydrofuran suchthat the reaction temperature did not exceed 50° C. Further, the mixturewas stirred at from 30 to 50° C. for 2 hours to complete the reaction.

Second Step

When the reaction mixture was cooled to room temperature, 200 ml ofdiethyl ether was added and then 50 ml of water was added portionwise.The reaction mixture was transferred into a separatory funnel and washedwith 80 ml of water, 60 ml of an aqueous 0.2 M tetramethylammoniumbromide solution, and 80 ml of water in order, and then concentrated. Tothe residue was added 200 ml of diethyl ether and the solids whichprecipitated were filtered to obtain 4.39 g (9.11 mmol) of the targetcompound as white solids in a yield of 91%.

Measurement of mass spectrum of the product gave a value of 407 for theanion portion and 74 for the cation portion, thus showing coincidencewith the calculated values. Also, elemental analysis indicatedcoincidence with the calculated values.

Elemental Analysis:

    ______________________________________                                        Calculated (%)                                                                             C 79.78 H 15.06   N 2.91                                                                              B 2.24                                     Found (%) C 79.99 H 15.11 N 2.79 B 2.11                                     ______________________________________                                    

EXAMPLE 3

Production of tetra-n-octylammonium benzyl triphenyl borate

First Step

To 1.00 g (41.1 mmol) of magnesium was added 10 mg of iodine. To thiswas added dropwise a solution of 5.18 g (33.0 mmol) of bromobenzene in20 ml of tetrahydrofuran in a nitrogen atmosphere to prepare a Grignardreagent.

The Grignard reagent was added dropwise in a solution of 2.20 g (10.0mmol) of diisopropyl benzyl boronate in 10 ml of tetrahydrofuran suchthat the reaction temperature did not exceed 50° C. Further, the mixturewas stirred at from 30 to 50° C. for 2 hours to complete the reaction.

Second Step

When the reaction mixture was cooled to room temperature, 200 ml ofdiethyl ether was added and then 50 ml of water was added portionwise.The reaction mixture was transferred into a separatory funnel, to whichwere added 80 ml of water and 5.5 g (11.8 mmol) of tetra-n-octylammoniumbromide, and washed with 80 ml of water, and then concentrated. To theresidue was added 200 ml of diethyl ether and the solids whichprecipitated were filtered to obtain 7.45 g (9.31 mmol) of the targetcompound as white solids in a yield of 93%.

Measurement of mass spectrum of the product gave a value of 333 for theanion portion and 466 for the cation portion, thus showing coincidencewith the calculated values. Also, elemental analysis indicatedcoincidence with the calculated values.

Elemental Analysis:

    ______________________________________                                        Calculated (%)                                                                             C 85.56 H 11.34   N 1.75                                                                              B 1.35                                     Found (%) C 85.48 H 11.31 N 1.99 B 1.22                                     ______________________________________                                    

EXAMPLE 4

Production of tetra-n-butylammonium n-butyltri(4-tert-butylphenyl)borate

First Step

To 1.00 g (41.1 mmol) of magnesium were added 10 mg of iodine, 1.42 g(10.0 mmol) of 2-n-butyl-1,3,2-dioxaborinane, and 10 ml oftetrahydrofuran. To this was dripped a solution of 7.03 g (33.0 mmol) of1-bromo-4-tert-butylbenzene in 20 ml of tetrahydrofuran in a nitrogenatmosphere such that the reaction temperature was from 67 to 72° C. andfurther the mixture was stirred at from 30 to 50° C. for 2 hours tocomplete the reaction.

Second Step

When the reaction mixture was cooled to room temperature, 200 ml ofdiethyl ether was added and then 50 ml of water was added portionwise.The reaction mixture was transferred into a separatory funnel and washedwith 80 ml of water, 60 ml of an aqueous 0.2 M tetra-n-butylammoniumbromide solution, and 80 ml of water in order, and then concentrated. Tothe residue was added 200 ml of diethyl ether and the solids whichprecipitated were filtered to obtain 6.80 g (9.57 mmol) of the targetcompound as white solids in a yield of 95%.

Measurement of mass spectrum of the product gave a value of 467 for theanion portion and 242 for the cation portion, thus showing coincidencewith the calculated values. Also, elemental analysis indicatedcoincidence with the calculated values.

Elemental Analysis:

    ______________________________________                                        Calculated (%)                                                                             C 84.58 H 11.92   N 1.97                                                                              B 1.52                                     Found (%) C 84.66 H 11.91 N 2.00 B 1.43                                     ______________________________________                                    

EXAMPLE 5

Production of tetra-n-butylammonium n-butyl tri(4-methylnaphthyl)borate

First Step

To 1.00 g (41.1 mmol) of magnesium were added 10 mg of iodine, 1.86 g(10.0 mmol) of diisopropyl n-butyl boronate, and 10 ml oftetrahydrofuran. To this was added dropwise a solution of 7.30 g (33.0mmol) of 1-bromo-4-methylnaphthalene in 20 ml of tetrahydrofuran in anitrogen atmosphere such that the reaction temperature was from 67 to72° C. and further the mixture was stirred at from 30 to 50° C. for 2hours to complete the reaction.

Second Step

When the reaction mixture was cooled to room temperature, 200 ml ofdiethyl ether was added and then 50 ml of water was added portionwise.The reaction mixture was transferred into a separatory funnel and washedwith 80 ml of water, 60 ml of an aqueous 0.2 M tetra-n-butylammoniumbromide solution, and 80 ml of water in order, and then concentrated. Tothe residue was added 200 ml of diethyl ether and the solids whichprecipitated were filtered to obtain 6.75 g (9.19 mmol) of the targetcompound as white solids in a yield of 91%.

Measurement of mass spectrum of the product gave a value of 491 for theanion portion and 242 for the cation portion, thus showing coincidencewith the calculated values. Also, elemental analysis indicatedcoincidence with the calculated values.

Elemental Analysis:

    ______________________________________                                        Calculated (%)                                                                             C 86.73 H 9.89    N 2.62                                                                              B 1.47                                     Found (%) C 86.91 H 9.63 N 2.44 B 1.19                                      ______________________________________                                    

EXAMPLE 6

Production of tetraethylammonium phenyl tri(2,5-dimethylphenyl)borate

First Step

To 0.3 g (43.2 mmol) of lithium was added 10 ml of diethyl ether. Tothis was added dropwise a solution of 6.11 g (33.0 mmol) of1-bromo-2,5-dimethylbenzene in 20 ml of diethyl ether in a nitrogenatmosphere such that the reaction temperature was from -75 to -65° C.and further the mixture was stirred at the same temperature as above for2 hours. This was added dropwise in a solution of 1.62 g (10.0 mmol) of2-phenyl-1,3,2-dioxaborinane in 10 ml of tetrahydrofuran such that thereaction temperature did not exceed 5° C. Further, the mixture wasstirred at from 0 to 5° C. for 2 hours to complete the reaction.

Second Step

When the reaction mixture was elevated to room temperature, 200 ml ofdiethyl ether was added and then 50 ml of water was added portionwise.The reaction mixture was transferred into a separatory funnel and washedwith 80 ml of water, 60 ml of an aqueous 0.2 M tetraethylammoniumbromide solution, and 80 ml of water in order, and then concentrated. Tothe residue was added 200 ml of diethyl ether and the solids whichprecipitated were filtered to obtain 3.80 g (7.10 mmol) of the targetcompound as white solids in a yield of 71%.

Measurement of mass spectrum of the product gave a value of 403 for theanion portion and 130 for the cation portion, thus showing coincidencewith the calculated values. Also, elemental analysis indicatedcoincidence with the calculated values.

Elemental Analysis:

    ______________________________________                                        Calculated (%)                                                                             C 85.53 H  9.82   N 2.62                                                                              B 2.03                                     Found (%) C 85.78 H 10.01 N 2.49 B 1.80                                     ______________________________________                                    

EXAMPLE 7

Production of tetraethylammonium cyclohexyl triphenyl borate

First Step

To 0.46 g (66.0 mmol) of lithium was added 10 ml of diethyl ether. Tothis was added dropwise a solution of 5.18 g (33.0 mmol) of bromobenzenein 20 ml of diethyl ether in a nitrogen atmosphere such that thereaction temperature was from -75 to -65° C. and further the mixture wasstirred at the same temperature as above for 2 hours. To this was addeddropwise a solution of 1.62 g (10.0 mmol) of2-cyclohexyl-1,3,2-dioxaborinane in 10 ml of tetrahydrofuran such thatthe reaction temperature was from 0 to 5° C. Further, the mixture wasstirred at from 0 to 5° C. for 2 hours to complete the reaction.

Second Step

When the reaction mixture was elevated to room temperature, 200 ml ofdiethyl ether was added and then 50 ml of water was added portionwise.The reaction mixture was transferred into a separatory funnel and washedwith 80 ml of water, 60 ml of an aqueous 0.2 M tetraethylammoniumbromide solution, and 80 ml of water in order, and then concentrated. Tothe residue was added 200 ml of diethyl ether and the solids whichprecipitated were filtered to obtain 4.21 g (9.00 mmol) of the targetcompound as white solids in a yield of 90%.

Measurement of mass spectrum of the product gave a value of 333 for theanion portion and 130 for the cation portion, thus showing coincidencewith the calculated values. Also, elemental analysis indicatedcoincidence with the calculated values.

Elemental Analysis:

    ______________________________________                                        Calculated (%)                                                                             C 84.37 H 10.81   N 3.07                                                                              B 2.37                                     Found (%) C 84.19 H 11.00 N 2.89 B 2.15                                     ______________________________________                                    

EXAMPLE 8

Production of tetramethylammonium n-butyl trinaphthyl borate

First Step

To a solution of 6.83 g (33.0 mmol) of 1-bromonaphthalene in 20 ml oftetrahydrofuran was added 21 ml (33.6 mmol) of 1.6 M n-butyllithiumunder ice cooling in a nitrogen atmosphere and the mixture was stirredfor 2 hours at the same temperature as above. This was added dropwise ina solution of 1.58 g (10.0 mmol) of diisopropyl ethyl boronate in 10 mlof tetrahydrofuran such that the temperature did not exceed 10° C.Further, the mixture was stirred at from 0 to 5° C. for 2 hours tocomplete the reaction.

Second Step

When the reaction mixture was elevated to room temperature, 200 ml ofdiethyl ether was added and then 50 ml of water was added portionwise.The reaction mixture was transferred into a separatory funnel and washedwith 80 ml of water, 60 ml of an aqueous 0.2 M tetramethylammoniumbromide solution, and 80 ml of water in order, and then concentrated. Tothe residue was added 200 ml of diethyl ether and the solids whichprecipitated were filtered to obtain 4.35 g (8.78 mmol) of the targetcompound as white solids in a yield of 87%.

Measurement of mass spectrum of the product gave a value of 421 for theanion portion and 74 for the cation portion, thus showing coincidencewith the calculated values. Also, elemental analysis indicatedcoincidence with the calculated values.

Elemental Analysis:

    ______________________________________                                        Calculated (%)                                                                             C 87.37 H 7.73    N 2.83                                                                              B 2.18                                     Found (%) C 87.51 H 7.80 N 2.59 B 2.23                                      ______________________________________                                    

EXAMPLE 9

Production of tetra-n-butylammonium butyltri(6-methoxy-2-naphthyl)borate

First Step

To 1.00 g (41.1 mmol) of magnesium were added 10 mg of iodine, 1.86 g(10.0 mmol) of diisopropyl n-butyl boronate, and 10 ml oftetrahydrofuran. To this was added dropwise a solution of 7.82 g (33.0mmol) of 2-bromo-6-methoxynaphthalene in 30 ml of tetrahydrofuran in anitrogen atmosphere such that the reaction temperature was from 67 to72° C. and further the mixture was stirred at from 30 to 50° C. for 2hours to complete the reaction.

Second Step

When the reaction mixture was cooled to room temperature, 200 ml ofdiethyl ether was added and then 50 ml of water was added portionwise.The reaction mixture was transferred into a separatory funnel and washedwith 80 ml of water, 60 ml of an aqueous 0.2 M tetra-n-butylammoniumbromide solution, and 80 ml of water in order, and then concentrated. Tothe residue was added 200 ml of diethyl ether and the solids whichprecipitated were filtered to obtain 7.11 g (9.10 mmol) of the targetcompound as white solids in a yield of 91%.

Measurement of mass spectrum of the product gave a value of 540 for theanion portion and 242 for the cation portion, thus showing coincidencewith the calculated values. Also, elemental analysis indicatedcoincidence with the calculated values.

Elemental Analysis:

    ______________________________________                                        Calculated (%)                                                                             C 81.41 H 9.28    N 1.79                                                                              B 1.38                                     Found (%) C 81.55 H 9.46 N 1.76 B 1.38                                      ______________________________________                                    

EXAMPLE 10

Production of tetra-n-butylphosphonium butyl trinaphthyl borate

First Step

To 1.00 g (41.1 mmol) of magnesium were added 10 mg of iodine, 1.86 g(10.0 mmol) of diisopropyl n-butyl boronate, and 10 ml oftetrahydrofuran. To this was added dropwise a solution of 6.83 g (33.0mmol) of 1-bromonaphthalene in 20 ml of tetrahydrofuran in a nitrogenatmosphere such that the reaction temperature was from 67 to 72° C. andfurther the mixture was stirred at from 30 to 50° C. for 2 hours tocomplete the reaction.

Second Step

When the reaction mixture was cooled to room temperature, 200 ml ofdiethyl ether was added and then 50 ml of water was added portionwise.The reaction mixture was transferred into a separatory funnel and washedwith 80 ml of water, 60 ml of an aqueous 0.2 M tetra-n-butylphosphoniumbromide solution, and 80 ml of water in order, and then concentrated. Tothe residue was added 200 ml of diethyl ether and the solids whichprecipitated were filtered to obtain 6.17 g (8.70 mmol) of the targetcompound as white solids in a yield of 87%. Measurement of mass spectrumof the product gave a value of 421 for the anion portion and 259 for thecation portion, thus showing coincidence with the calculated values.Also, elemental analysis indicated coincidence with the calculatedvalues.

Elemental Analysis:

    ______________________________________                                        Calculated (%)                                                                            C 84.73     H 9.39  B 1.53                                          Found (%) C 84.90 H 9.55 B 1.77                                             ______________________________________                                    

EXAMPLE 11

Production of tri-n-butylsulfonium butyl trinaphthyl borate

First Step

To 1.00 g (41.1 mmol) of magnesium were added 10 mg of iodine, 1.86 g(10.0 mmol) of diisopropyl n-butyl boronate, and 10 ml oftetrahydrofuran. To this was added dropwise a solution of 6.83 g (33.0mmol) of 1-bromonaphthalene in 20 ml of tetrahydrofuran in a nitrogenatmosphere such that the reaction temperature was from 67 to 72° C. andfurther the mixture was stirred at from 30 to 50° C. for 2 hours tocomplete the reaction.

Second Step

When the reaction mixture was cooled to room temperature, 200 ml ofdiethyl ether was added and then 50 ml of water was added portionwise.The reaction mixture was transferred into a separatory funnel and washedwith 80 ml of water, 60 ml of an aqueous 0.2 M tri-n-butylsulfoniumiodide solution, and 80 ml of water in order, and then concentrated. Tothe residue was added 200 ml of diethyl ether and the solids whichprecipitated were filtered to obtain 5.88 g (9.00 mmol) of the targetcompound as white solids in a yield of 90%. Measurement of mass spectrumof the product gave a value of 421 for the anion portion and 203 for thecation portion, thus showing coincidence with the calculated values.Also, elemental analysis indicated coincidence with the calculatedvalues.

Elemental Analysis:

    ______________________________________                                        Calculated (%)                                                                             C 84.63 H 8.80    S 4.91                                                                              B 1.65                                     Found (%) C 85.00 H 9.01 S 4.77 B 1.82                                      ______________________________________                                    

EXAMPLE 12

Production of diphenyliodonium butyl trinaphthyl borate

First Step

To 1.00 g (41.1 mmol) of magnesium were added 10 mg of iodine, 1.86 g(10.0 mmol) of diisopropyl n-butyl boronate, and 10 ml oftetrahydrofuran. To this was added dropwise a solution of 6.83 g (33.0mmol) of 1-bromonaphthalene in 20 ml of tetrahydrofuran in a nitrogenatmosphere such that the reaction temperature was from 67 to 72° C. andfurther the mixture was stirred at from 30 to 50° C. for 2 hours tocomplete the reaction.

Second Step

When the reaction mixture was cooled to room temperature, 200 ml ofdiethyl ether was added and then 50 ml of water was added portionwise.The reaction mixture was transferred into a separatory funnel and washedwith 80 ml of water, 60 ml of an aqueous 0.2 M diphenyliodonium bromidesolution, and 80 ml of water in order, and then concentrated. To theresidue was added 200 ml of diethyl ether and the solids whichprecipitated were filtered to obtain 6.43 g (9.10 mmol) of the targetcompound as white solids in a yield of 91%. Measurement of mass spectrumof the product gave a value of 421 for the anion portion and 281 for thecation portion, thus showing coincidence with the calculated values.Also, elemental analysis indicated coincidence with the calculatedvalues.

Elemental Analysis:

    ______________________________________                                        Calculated (%)                                                                            C 74.80     H 5.70  B 1.53                                          Found (%) C 74.78 H 5.88 B 1.62                                             ______________________________________                                    

INDUSTRIAL APPLICABILITY

According to the present invention, a high purity boron-based compoundrepresented by the general formula (1) above useful as aphotopolymerization initiator and a light-absorbing decolorizing agentcan be obtained in a short time and a high yield as compared with theconventional method.

What is claimed is:
 1. A method of producing a boron-based compoundrepresented by general formula (1) ##STR8## (wherein R¹ and R²independently represent an alkyl group which may have a substituentgroup, an alkenyl group which may have a substituent group, an arylgroup which may have a substituent group, an aralkyl group which mayhave a substituent group, a heterocyclic group which may have asubstituent group, or an alicyclic group which may have a substituentgroup provided that R¹ and R² are different from each other and Z⁺represents an ammonium cation, a pyridinium cation, a sulfonium cation,an oxosulfonium cation, a phosphonium cation, or a iodonium cation),comprising a first step of reacting lithium, magnesium or a compoundcontaining lithium; and a compound represented by general formula (2)##STR9## (wherein R¹ has the same meaning as defined above, R⁷ and R⁸,which may be the same or different, each represent an alkyl group whichmay have a substituent group, an alkenyl group which may have asubstituent group, an aryl group which may have a substituent group, anaralkyl group which may have a substituent group, or an alicyclic groupwhich may have a substituent group, or R⁷ and R⁸ combine with each othertogether with the boron atom and oxygen atoms to which they are attachedto form a cyclic structure); and a compound represented by generalformula (3)

    R.sup.2 --Y                                                (3)

(wherein R² has the same meaning as defined above and Y represents ahydrogen atom or a halogen atom) to produce a borate metal saltrepresented by general formula (4) ##STR10## (wherein R¹ and R² have thesame meanings as defined above, M is lithium or magnesium and n is 1when M is lithium or 2 when M is magnesium), and a second step of addingto the borate metal salt an onium halide represented by general formula(5)

    Z.sup.+ ·X.sup.-                                  ( 5)

(wherein Z⁺ has the same meaning as defined above and X⁻ represents ahalide anion) to effect ion exchange reaction.
 2. The method ofproducing a boron-based compound represented by general formula (1) asclaimed in claim 1, wherein the onium halide represented by the generalformula (5) is an ammonium halide represented by general formula (6)##STR11## (wherein X⁻ has the same meaning as defined above and R³, R⁴,R⁵, and R⁶ independently represent an alkyl group which may have asubstituent group, an aryl group which may have a substituent group, anaralkyl group which may have a substituent group, or an alicyclic groupwhich may have a substituent group).
 3. The method of producing aboron-based compound represented by the general formula (1) as claim 1or 2, wherein in the first step, lithium, magnesium or the compoundcontaining lithium and the compound represented by the general formula(3) are reacted in a solvent and then the compound represented by thegeneral formula (2) is added to obtain the borate metal salt representedby the general formula (4).
 4. The method of producing a boron-basedcompound represented by the general formula (1) as claim 1 or 2, whereinin the first step, a product obtained by reacting lithium, magnesium orthe compound containing lithium and the compound represented by thegeneral formula (3) in a solvent is added to the compound represented bythe general formula (2) to obtain the borate metal salt represented bythe general formula (4).
 5. The method of producing a boron-basedcompound represented by the general formula (1) as claim 1 or 2, whereinin the first step, lithium, magnesium or the compound containing lithiumand the compound represented by the general formula (3) are reacted in asolvent in the presence of the compound represented by the generalformula (2) to obtain the borate metal salt represented by the generalformula (4).
 6. The method of producing a boron-based compoundrepresented by the general formula (1) as claimed in claim 1 or 2,wherein in the first step, lithium or magnesium is used and a halide isused as the compound represented by the general formula (3).
 7. Themethod of producing a boron-based compound represented by the generalformula (1) as claimed in claim 1 or 2, wherein in the first step, anorganic lithium compound is used and a halide is used as the compoundrepresented by the general formula (3).
 8. The method of producing aboron-based compound represented by the general formula (1) as claimedin claim 3, wherein in the first step, lithium or magnesium is used anda halide is used as the compound represented by the general formula (3).9. The method of producing a boron-based compound represented by thegeneral formula (1) as claimed in claim 4, wherein in the first step,lithium or magnesium is used and a halide is used as the compoundrepresented by the general formula (3).
 10. The method of producing aboron-based compound represented by the general formula (1) as claimedin claim 5, wherein in the first step, lithium or magnesium is used anda halide is used as the compound represented by the general formula (3).11. The method of producing a boron-based compound represented by thegeneral formula (1) as claimed in claim 3, wherein in the first step, anorganic lithium compound is used and a halide is used as the compoundrepresented by the general formula (3).
 12. The method of producing aboron-based compound represented by the general formula (1) as claimedin claim 4, wherein in the first step, an organic lithium compound isused and a halide is used as the compound represented by the generalformula (3).
 13. The method of producing a boron-based compoundrepresented by the general formula (1) as claimed in claim 5, wherein inthe first step, an organic lithium compound is used and a halide is usedas the compound represented by the general formula (3).